In scientific discovery, there is a difference between hearing of a left ear and a right ear of each person, particularly some people suffered from an ear disease may have a big binaural hearing difference. A foreign hearing survey in 1998 shows approximately 1 percent of children at school suffer from one-side hearing loss. A survey by Chinese Journal of Pediatrics in 2009 shows that a hearing loss rate of middle school students in Xi'an is 2.30%. According to statistics, there are approximately 27.8 million of people with hearing impairment currently in our country, which occupy the maximum amount among various disabled people. In addition, influenced by air pollution, noise, frequent use of an earphone to listen to a music, and the like, the amount of people with hearing impairment is increasing.
For users having a hearing difference between a left ear and a right ear, there is much inconvenience when they answer a call. When calling for a long time, they may feel uncomfortable if answering the call on one side for a much longer time, and thus generally may answer the call with the left ear and the right ear alternatively; in this situation, if an earphone volume is unchanged, the users may feel that the voice is too loud or too low. When they frequently transfer the phone between the left ear and the right ear, they need to continuously adjust the volume, which may influence their mood when calling, and thus they feel unsatisfied with a mobile phone. In addition, a left half and a right half of a brain may have different ways to process the sound, and therefore when the sound is heard, two ears may adopt different ways for processing. The left ear is most sensitive to a music, while the right ear may obtain a voice better.
When a left ear and a right ear of a user is alternatively used in a call, since hearing of the left ear and the right ear is different, the user usually needs to continuously adjust volume of an earphone manually, which results in much inconvenience when answering the call.